What is a circumference?

Circumference is the distance of the outside of the circle. It's basically the perimeter of the circle.













-the outside circle indicates the circumference



The formula for circumference is 2pr(2 x p x r).

 e.g.

    The radius is 3m, what is the circumference?


    A=2pr
    A=2 x 3.14 x 3
    A=6.28 x 3
    A=18.84m
     

 

Formula for Area

Area is the amount of surface the circle covers. It is measured in squared units.







The formula for area is pr2(pi x r squared).




e.g.

    the radius is 2m, what is the circumference?
       
    A=pr2
    A=3.14 (2)2
    A=3.14 x 2 x 2
    A=6.28 x 2
    A=12.56 m2




   You always need to put the units you are working with.
    Explaining it like this will give an accurate answer.

Diameter

Diameter- The distance across a circle through its center 

Circumference

Circumference - distance around the circle.
Formula:
C = πd
C = 2πr

click here for a link about Circumference.

Radius

Radius- (Plural is Radii) The Distance from the center of a circle to its outer edge

What is a diameter?

Diameter is part of a circle. It is a measurement across from a one point on a side of a circle going through the center point the onto the other side. The formula for diameter is 2r=d. 2 radii is equal to 1 diameter.

Radius

Half the diameter of a circle.